MIC3205 Datasheet, PDF (1/23 Pages) Micrel Semiconductor – High-Brightness LED Driver Controller with Fixed-Frequency Hysteretic Control

MIC3205
High-Brightness LED Driver Controller
with Fixed-Frequency Hysteretic Control
General Description
The MIC3205 is a hysteretic, step-down, high-brightness
LED (HB LED) driver with a patent pending frequency
regulation scheme that maintains a constant operating
frequency over input voltage range. It provides an ideal
solution for interior/exterior lighting, architectural and
ambient lighting, LED bulbs, and other general illumination
applications.
The MIC3205 is well suited for lighting applications
requiring a wide input voltage range. The hysteretic control
provides good supply rejection and fast response during
load transients and PWM dimming. The high-side current
sensing and on-chip current-sense amplifier deliver LED
current with 5% accuracy. An external high-side current-
sense resistor is used to set the output current.
The MIC3205 offers a dedicated PWM input (DIM) which
enables a wide range of pulsed dimming. A high-frequency
switching operation up to 1.5MHz allows the use of smaller
external components minimizing space and cost.
The MIC3205 operates over a junction temperature from
–40°C to +125°C and is available in a 10-pin 3mm x 3mm
MLF^® package.
Data sheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Features
 4.5V to 40V input voltage range
 Fixed operating frequency over input voltage range
 High efficiency (90%)
 5% LED current accuracy
 High-side current sense
 Dedicated dimming control input
 Hysteretic control (no compensation!)
 Up to 1.5MHz switching frequency
 Adjustable constant LED current
 Over-temperature protection
 –40C to 125C junction temperature range
Applications
 Architectural, industrial, and ambient lighting
 LED bulbs
 Indicators and emergency lighting
 Street lighting
 Channel letters
 12V lighting systems (MR-16 bulbs, under-cabinet
lighting, garden/pathway lighting)
_________________________________________________________________________________________________________________________
Typical Application
Normalized Switching Frequency
vs. Input Voltage
2.0
I_LED = 1A
R_CS = 0.2Ω
1.5
1 LED
L = 22µH
1.0
4 LED
0.5 L = 47µH
6 LED
L = 68µH
10 LED
L = 33µH
0.0
0
9
18
27
36
45
INPUT VOLTAGE (V)
MIC3205 Buck LED Driver
MLF and MicroLeadFrame are registered trademarks of Amkor Technology, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
October 2012
M9999-102312-A